<!--
 * @Author: your name
 * @Date: 2021-08-16 17:24:37
 * @LastEditTime: 2021-08-17 16:42:08
 * @LastEditors: Please set LastEditors
 * @Description: 优先级
 * @FilePath: \第一周\day03\优先级.html
-->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>优先级</title>
    <style>
        ul.menu {
            color: gray;
        }
        ul.menu > li.menu_item {
            color: gray;
        }
        ul.menu > li.menu_item > ul.sub_menu {
            color: gray;
        }
        /* 复用：标签选择器、class选择器、子选择器 */
        ul.menu > li.menu_item > ul.sub_menu > li {
            color: lightcoral;
            line-height: 2em;
        }
        /* id选择器（100） */
        #introduce {
            color: lightgreen;
            background-color: lightcoral;
        }  
        .si {
            color: gray !important;
            border: 3px solid gray;
        }

    </style>
</head>
<body>
    <div class="tyut">
        <!-- 头部 -->
        <header>
            <div class="first_line"></div>
            <div class="second_line">
                <div class="logo">logo</div>
                <!-- ul菜单列表 -->
                <ul class="menu">
                    <li class="menu_item">
                        <span>学校概况</span>
                        <ul class="sub_menu">
                            <li class="si" style="color: blue;" id="introduce">学校简介</li>
                            <li id="history">历史沿革</li>
                        </ul>
                    </li>
                    <li class="menu_item">
                        <span>人才培养</span>
                        <ul class="sub_menu">
                            <li>本科生教育</li>
                            <li>研究生教育</li>
                        </ul>
                    </li>
                    <li class="menu_item">
                        <span>科学研究</span>
                        <ul class="sub_menu">
                            <li></li>
                            <li></li>
                        </ul>
                    </li>
                </ul>
            </div>
        </header>
    </div>
</body>
</html>
